1. Field of the Invention
The invention relates in general to a pushbutton device for controlling electric apparatus and in particular to an interlock mechanism for dual or multiple linearly operated operators, of which a pushbutton device is a common example.
2. Description of the Prior Art
Interlock mechanisms for interlocking two pushbuttons are well known in the prior art. They may require mechanical linkages or complex assemblies. In addition, interlock devices of the prior art, if they are sized large enough to prevent breakage or mechanical damage when subjected to actuation, generally may cause a problem due to the necessity to accelerate the large mass during actuation of either pushbutton. Conversely, if the interfering member is made lighter to promote ease of actuation, this causes problems with damage to the interfering member by an enthusiastic operator. Accordingly it would be desirable to have an interlock mechanism requiring no mechanical linkages or complex assemblies, and it would further be desirable for the interfering portion of the interlock mechanism to have a small relative mass which actuates an interfering portion of great strength smoothly and provides the essential function of making it impossible to actuate both operators concurrently.